One of the attractions of the original Colonization game are its many
small features that sometimes affect game play in subtle and
unexpected ways. Although we have been working on implementing all
these features for years, we still haven't completed the job.
Recently, we were made aware of one feature that had escaped our
attention so far: Inca and Aztec cities, as well as native capitals
have a higher defence bonus than other native settlements.

Adding special cases to handle these bonuses would have been pretty
simple, but would have added more hard-coded modifiers to the game.
As it turned out, the combat model already contained about half a
dozen hard-coded modifiers interfering with our on-going effort to
make FreeCol more configurable. The (more or less) obvious solution
was to move these modifiers to the specification. This, of course,
created several smaller problems, which seem to have been fixed,
however.

The net result of the changes is that you can now tune six modifiers
that directly affect the combat model, such as the defence bonus
granted to a fortified unit. Nation types now have two additional
modifiers, namely the settlement defence modifier and the capital
defence modifier, which are added to the defensive modifiers of all
units defending these settlements. At the moment, European nation
types do not make use of the capital defence modifier, since they do
not have capitals, but this might well be changed in the future.